All posts tagged 2013 melt season

All the updates are in and with the major melt month of June now in the rear view mirror, it’s time take a fresh look at the volatile melt season of 2013.

In short, June melt proceeded rapidly, but not rapidly enough to break into new record territory after the slow melt month of May. Meanwhile, PAC 2013, which turned a large section of the central Arctic into a mush of broken ice faded as high pressure began to deepen and exert its own unique sets of influences over the region. As the clouds broke, air temperatures began to heat up in the Central Arctic even as anticyclonic pumping began to pull ice into the large hole formed by the storms of June. Above average temperatures ruled much of the Arctic edge as Scandinavia and North-Eastern Europe, Siberian Kamchatka, Eastern Alaska and Central Canada all showed hotter than normal conditions. The high, entrenching itself, began to pool warm air directly over the Arctic’s fractured heart…

Major Monitors Show 2013 Melted Rapidly in June through early July, But Not Rapidly Enough to Break into New Record Territory

A combination of a storm thinning the ice of the Central Arctic and hot air pulses rushing in from the ice edge resulted in a near record pace of melt for sea ice area, volume, and extent during June through early July. This furious pace of melt was fast enough to challenge previous record lows, if not to break them.

Sea ice extent measures produced by NSIDC provide a good allegory for the overall melt trend seen in June through early July. In early to mid June, extent melt proceeded at a gradual pace at first. By late June and into early July, extent melt had drastically increased showing multiple days of 150,000 kilometer or greater loss. This extraordinarily steep pace of melt can be seen in the above graph. If such a rapid pace continues through mid July, a new record low extent level will be breached.

Currently, sea ice extent is 6th lowest on record and is only slightly above the 2007 melt line. This puts sea ice extent, according to NSIDC, about 1.4 million square kilometers below the 1979-2000 average.

To this point, it is important to consider that NSIDC has now included the extreme melt decade of 2000-2010 in its official records. So NSIDC ‘averages’ on site include these shifting goal-posts. The data set includes a declining curve and, therefore, cannot be seen entirely as ‘normal.’ Instead, it provides an anomaly base-line for a highly anomalous period and should be viewed as such. To the superficial observer, presenting the data in this fashion will somewhat serve to mask what can best be described as a sea ice death spiral. A plain example of this discrepancy is the fact that 1979 sea ice values for the same date (July 8) were about 2.1 million square kilometers higher than today. A severe decline by any measure. It is worth noting, though, that NSIDC does provide a very useful interactive tool in which all sea ice extent records are available here. (Hat-tip to Physicist-retired who provided this link in the comments section below).

Pace of sea ice area melt was also rapid during the month of June through early July with more than 4 million square kilometers lost during the five-week period. As a result, sea ice area measurements are now around 4th or 5th lowest in the record or about 1.8 million square kilometers below 1979 values. Though rapid, this melt rate still puts current measures about 800,000 square kilometers above record low totals seen for this date in 2012. So area melt will have to be steep, indeed, for new records to be reached by end of summer.

The critical measure of sea ice volume showed a quickening pace of decline from mid-May to mid-June. PIOMAS showed volume levels about tied with 2010 as third lowest in the measure by about June 15th. PIOMAS tends to lag a bit behind area and extent. So we don’t yet have an idea of where volume stands come early July.

That said, it is important to note that much of the region usually covered with thick ice — the Beaufort and the area north of Greenland and the CAA are substantially thinned compared to previous years. NASA’s Ice Bridge survey found this region about 8% thinner during March and April of 2013 than during the same period of 2012. Thinner ice in regions that are typically the bastion for thick ice during late summer may show much more rapid melt in July and August (especially at times when strong high pressure systems dominate the Central Arctic).

Note the large region where ice thickness is 2 meters or less from the middle Canadian Archipelago and stretching on into the Beaufort. A large pulse of melt now advances from the Chukchi and along the coast of Canada and Alaska into this region. A persistent blocking pattern has also driven pulses of much warmer than normal air into this area consistently throughout June. Weather models forecast additional atmospheric warming through at least mid July. With a strong high pressure ridge now forming in the Central Arctic, this region will be one to watch for potentially rapid melt as July progresses into August.

High Pressure Forms in the Wake of PAC 2013

The dominant feature of the Central Arctic during June of 2013, a Persistent Arctic Cyclone that turned a large section of this region into an icy slurry, finally faded as of last week. The impact of this storm has now been widely accepted with NSIDC providing expert analysis on the subject:

High-resolution passive microwave concentration data from the Japan Aerospace Exploration Agency AMSR2 sensor, produced by the University of Bremen, indicate a highly unusual region of broken-up ice near the North Pole. Development of this low concentration ice may have been assisted by the cyclonic atmospheric pattern noted earlier.

…MODIS data do confirm that the ice is highly fractured with numerous small floes. Such small floes are more easily melted from the sides and the bottom by ocean waters that are exposed to the 24-hour sunlight. It remains to be seen how many of these small floes will ultimately melt completely (emphasis added).

This condition may become particularly evident as the dipole switches from storm over the Central Arctic to clear air, warmer temperatures and higher pressure. A 1020 millibar high has already formed over the central Arctic and is expected to heighten into a 1030 millibar high by the middle of July. This thickening high will bring sunny conditions and much warmer air temperatures to the Central Arctic. It will also create an anti-cyclonic down-welling near its center. This pumping action will tend to have the effect of drawing edge ice into the hole created by PAC 2013. If the waters in the hole are substantially warmed, it is possible that enhanced melt will occur in this region even as edge ice is drawn back into the hole.

You can see some of this potential melt action predicted in the US Navy CICE model run for the 30 days from mid June through the end of next week:

The effect a high like the one predicted has on sea ice is clearly demonstrated at the end of the above model run. The down-welling in the Central Arctic is seen to suck large portions of the ice in this region toward the hole formed by PAC 2013. At the edges, an upwelling action combines with counter-clockwise winds around the high to pull the ice edge inward even as the warmer upwelling waters eat away at the outliers. Note the rapid drawing in of all ice from the Beaufort, East Siberian Sea, Laptev and in a broad region north of Svalbard.

This action is the exact opposite of the effect seen during June via the impacts of PAC 2013. Then, a storm created an anomalous hole in the central sea ice even as it shoved ice toward warmer regions. Now, the rapid switch from storm conditions to strong high pressure conditions creates the potential for another unusual event: the collapse of thick ice and edge ice into the hole PAC created. Such an event would likely have an amplified effect on sea ice melt, especially in the extent measures. So we’ll will have to keep a close eye on both this building high pressure system and its interaction with the hole created by PAC 2013. Should these CICE model runs bear out, the next few weeks will be extraordinarily interesting.

It is also important to note that CICE only shows impacts through July 15th. Yet, according to ECMWF weather forecasts, a strong, 1030 millibar high is expected to last in the Central Arctic at least until July 18th.

Arctic Heat Dome Starting to Form?

To this point, it is worth noting that the weather models indicate a potential for yet another extreme Arctic weather event: the formation of an Arctic ‘heat dome.’

ECMWF forecasts show a powerful high pressure ridge developing over the Central Arctic through mid July. Associated with this high is a river of warmer air that is predicted to run directly over the North Pole. Indications are for 40 degree plus average temperatures at the 5,000 foot level by July 18th. This translates to average surface temperatures as high as the mid 50s over a broad section of the Beaufort, through the North Pole and on over to Svalbard. For the high Arctic, which averages just above freezing for this time of year, that’s a heatwave.

The establishment of this ‘dome’ high pressure system has already begun with a 1020 millibar high strengthening over the Laptev and Central Arctic. Should this ‘heat dome’ continue to strengthen and entrench as predicted, it is likely that edge melt will be greatly enhanced even as thicker ice is pulled into the melt hole created by PAC 2013 as July progresses.

The formation of such a strong high and associated warmer atmospheric temperatures during July is not conducive for ice preservation. In fact, the formation of this kind of weather system would have resulted in hastening melt even during times when the ice was thicker and more resilient. Instead, the ice suffered at the hands of a storm that, typically, would have helped preserve it. Now, the formation of a powerful high pressure system threatens a crowning blow.

So an interesting and volatile melt season continues. Anomalous storm melting of Central Basin sea ice appears to be transitioning to a powerful regime of high pressure that threatens to bring much warmer temperatures to the Central Arctic all while drawing edge ice into the deep melt hole formed by PAC 2013.

Well, it’s official. PAC 2013 has yet to give up the ghost. After transitioning to the Canadian Archipelago, it has now formed a trough composing three low pressure centers that roughly straddles Greenland, Baffin Bay, and the thickest sea ice. At this point, the storm is nearly one month old (with a formation date around May 21-26). Lowest pressures appear to be around 990 mb, but the entire region is covered in rough weather and clouds.

A look at the heat map shows the storm pulling in warmer air from the Alaskan side of the Arctic and from regions around it. This extra energy has given it enough to fuel multiple lows for an extended period. As a by-product, many regions over the Central Arctic are now above freezing. Areas near the low pressure centers still show temperatures in the range of 0 to -3 Celsius. But a broad swath of above-freezing temperatures are now under the circulation of this, rather large, storm.

On the map, we also notice areas of high heat concentration centered over Scandinavia, Central Siberia, Alaska, and just West of Hudson Bay. These regions of heat are both potential launching pads for more warm air invasions of the Arctic as well as feeding sources for our storm, should it continue.

And, according to forecasts, we can find that this storm isn’t done by a long-shot. ECMWF model runs show it forming troughs with numerous low pressure cells and chewing through large portions of the Arctic all the way through to July 1. Seems we were right to caution against an end to PAC 2013 in this earlier blog.

A very interesting example is the ECMWF forecast for June 27th when PAC 2013 forms a sprawling trough from the East Siberian Sea to Baffin Bay to Greenland to the Kara. It is a trough composed of not one, not two, but at least six separate low pressure cells. The forecast for tomorrow through much of the model run shows similar configurations with daisy chains of storms linked by a trough swirling along through the Arctic.

These model runs would seem to indication very stormy conditions not only for the Central Arctic, but for the periphery as well.

The ‘Warm’ Arctic Storm Begins to Emerge?

With temperatures rising to above freezing in the Central Arctic Basin and with storms projected to persist at least until July 1rst, we may receive an unwelcome glimpse of the ‘Warm’ Storm described here. Previously, I had speculated that ‘Warm’ Storm conditions would be present with moderate-to-strong cyclones persisting in the Central Arctic at a time when air temperatures ranged from 0 to 6 degrees Celsius. As we can see from the temperature map at the top of the post, we are not far off from that threshold now. And with heatwaves popping up around the Arctic there is more than enough warmth to push Central Arctic temperatures higher over the coming days and weeks.

Over at the Arctic Ice Blog (read it, join it, follow it, chat on it — you will learn boatloads), expert posters Wayne and R. Gates have noted that while clouds block direct sunlight, they can act to trap long-wave radiation. R. Gates had also linked a recent scientific study which showed that cloudy conditions from March to May enhanced rather than inhibited melt. The energy of this long-wave radiation would transfer directly to ice and ocean, so atmospheric temperatures would not be directly impacted. But more heat content in the waters and ice, overall, might be providing some of the extra kick that ECMWF appears to have missed. Another recent study by Edward Hanna found that low level clouds helped to increase the record Greenland ice sheet melt of 2012 (study here) by trapping heat near the ice. So the overall effect of clouds in cooling is less certain than one would think at first blush.

Another source of this extra heat may be via the ocean itself. As noted in previous posts, cyclonic action creates a kind of pumping force (Ekman), that can pull water up from the ocean’s depths. In the Arctic, the surface layer is cold. But underneath lies a layer of warm water fueled by the inflow from oceans surrounding the Arctic (primarily the Atlantic). As commenter Johnm33 noted, once a strong inflow of upwelling water is established, it is possible that yet more warm water is being drawn into the deep Arctic Ocean from the Atlantic. If this warmer inflow was pumped to the surface, it would add to atmospheric heat beneath the storm.

Lastly, the atmosphere, via high amplitude waves in the Jet Stream is now also providing its own source of heat by dredging deep into the lower latitudes and pulling warmer air up into the Arctic. So far this summer, we have seen record heat waves in both Scandinavia and Alaska. These heat waves were caused by persistent blocking patterns that injected heat into these Arctic locations. Scandinavia saw temperatures in the 80s, Alaska saw temperatures rocketing into the upper 90s. The Jet Stream configuration allowing for these hot air injections at these locations still persists and are plainly visible on the current Jet Stream map:

Note the large wave in the Jet Stream (and associated warmer air) now riding up over Alaska and deep into the Beaufort, Chukchi, and East Siberian Seas. Another pulse is visible lunging up through Scandinavia. A third, though less southwardly linked, pulse is also now rising over Eastern Siberia. These extraordinarily high amplitude waves all cross far beyond the Arctic Circle. An atmospheric condition that is anything but normal and one that is also continuing to supply warmer air to the Arctic environment, even one covered by a storm that would normally substantially cool the atmosphere there (for more information on how snow and ice melt in the Arctic is enabling these high amplitude Jet Stream waves, take a look at some of the work of Dr Jennifer Francis). Instead, as the discrepancy with ECMWF predictions and surface observations shows, we have temperatures that are only .5 to 1 degree C cooler than average under the storm (they should be about 3-7 C cooler) and much, much warmer conditions surrounding it.

A Warm Storm persisting in the Central Arctic for long periods is a potential nightmare scenario for sea ice melt. Currently, we have warming conditions in the Central Arctic, a spate of record heat-waves at the periphery in places like Alaska and Scandinavia, a mangled Jet Stream that keeps pumping warmer air into the Arctic, and a storm that is now projected to persist until at least July 1rst. So we now have to consider at least the temporary emergence of the Warm Storm to be a possibility going forward.

Impacts to Sea Ice Still Ongoing, Likely to Ramp Up

A substantial thinning and chopping up of the sea ice is now apparent in all visible (when you can see through the clouds), concentration, and thickness monitors. Now, a wasteland of thinned, shattered and broken ice is visible in a swath from Svalbard all the way to Wrangle Island near the Bering Strait. A comprehensive graphic summary of these impacts is provided below:

The current image, provided by the US Navy is a stark contrast to conditions seen at the end of May. This thickness measure shows a long ‘claw’ of much thinner ice reaching all the way in to the Central Arctic and encompassing the North Pole. This graphic reveals very poor Central Ice thickness conditions for mid-to-late June.

Uni-Bremen has been providing consistent confirmation of ice damage and fragmentation due to the Ongoing Arctic Storm for nearly two weeks now. Here’s the most recent concentration monitor showing the broad swath of broken ice.

And Cryosphere Today, which is less sensitive than the other monitors shows low ice concentrations stretching from Svalbard to Wrangle Island.

Overall, should PAC 2013 continue to warm even as it persists, it should have ever-greater deleterious effects on the Central Arctic sea ice as mid-to-late June transitions into July. The US Navy thickness forecast shows ongoing thinning and fracturing in this region all the way through June 28th. One interesting feature of note in this forecast is that it appears a substantial section of ice will be separated from the main pack and stranded in the Kara Sea if current trends continue through early July.

So, apparently against all odds, PAC 2013 continues and, even worse, shows risk of beginning a transition to a ‘Warm’ Storm in the Central Arctic. Should this trend remain in effect, increasingly visible damage to the central ice is likely to become ever more apparent as June turns to July.